Physics Investigation of Gymnastics

The described physics involved in these gymnastics skills are somewhat
simplified, for the movement of the human body encompasses other specific
forces, particularly those studied in the field of biomechanics. For a better
understanding of the physics of theses skills, here is a brief discription of
the forces involved in muscle contraction as discribed by William L. Cornelius,
Ph.D in a 1997 issue of Technique (Vol.17, No.1), a gymnastics
magazine:

Internal Muscular Force Muscular strength is considered to be the ability to do
work against resistance or the capacity to exert force Arnheim and Prentice,
1993) and is derived through muscle tension produced during muscle contraction.
The outcome is a force internal to the human system. This internal force
produces tension on the skeletal system, resulting in angular motion about a
joint. Examples of this phenomenon are shown in Figures 2-4 by furnishing
illustrations of gymnastics movements and associated muscle forces.

Resolution of force

Resolution of force or vector resolution is an example of a biomechanical
technique that provides a means of establishing the two component forces
directly associated with a net force. This net force can be responsible
for a movement and is known as the resultant force (Figure 1). An
explanation is now possible for why a particular force results in a
specific movement when the resultant vector is known. This leads to
resolving the component forces. Component forces provide a clearer
picture of what the resultant force contributes to the performance.

Component forces

Angular and stabilizing vectors represent the
two components derived from a resultant force. Figure 1 illustrates the
relationship between the resultant vector and component forces. When dealing
with internal forces created from muscle contractions, the resultant force (F)
is applied at the muscle insertion located on the attachment (apophysis) of the
bone to be mobilized and is directed toward the muscle origin. This resultant
force is directed through the belly of the particular muscle. The angular vector
is directed perpendicular to the bone that is being moved and the stabilizing
vector is directed along the same bone, into the joint (Kreighbaum and Barthels,
1996). Consequently, the angular force component is responsible for moving the
skeletal part, while the stabilizing force component serves as a means of adding
to joint integrity (stability). The angular vector (F1) and stabilizing vector
(F2) begin from the point of force application and are directed at right angles,
one to the other. Figures 2-4 provide examples of resultant vectors and their
component vectors, originating from concentric muscle contractions during the
performance of gymnastics skills.